I watched the complete Carlin HBO specials about five years ago, from the 1970s up to the last one he did, and they are very anodyne at the beginning. Having watched a few documentaries about his career, they don't necessarily reflect the risks he was taking live sometimes; but really, if you watch those specials, he seems to evolve from a tediously corporate comedian into a hilarious and unstoppable force of nature. So I can understand how people would have the perception that he started out generic, as that was what the public saw in popular output he made.